A 28-year-old G3P2 with two prior cesarean sections undergoes ultrasound at 24 weeks. The placenta is anterior and low-lying. Color Doppler shows lacunae and loss of retroplacental clear zone. The MOST specific ultrasound feature that predicts placenta percreta (invasion through serosa) rather than accreta is:

• A Multiple intraplacental lacunae (Swiss cheese appearance)
• B Loss of retroplacental hypoechoic zone
• C Turbulent lacunar flow on Doppler
• D Bridging vessels extending from placenta to bladder wall ✓

Explanation

Bridging vessels extending from the placenta to adjacent organs (particularly the bladder) on color Doppler are specific for placenta percreta, indicating trans-serosal invasion. Lacunae and loss of retroplacental clear zone are features common to placenta accreta spectrum broadly. Turbulent lacunar flow suggests deep invasion but does not localize to percreta. Bladder involvement with bridging vessels carries the highest surgical risk.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.